Is it possible to grow hair on a bald spot due to injury? (Photo)

Yes the bald spot is scar tissue, I'm sure. Grafts will grow in scar tissue, though not as densely packed as normal tissue. Therefore you may need two small transplants to get the coverage required to adequately cover the area of scarring.

This is a scar. One can consider a few options including a hair transplant, cutting the area out (i.e. excision) or scalp micropigmentation. Please visit a hair transplant surgeon for guidance at this time.

It looks like you sustained lacerations on the scalp and the areas of scarring which do not have hair, can not grow hair with medications. Hair transplants into the scars will work